I used to share the same profile across Windows/Linux/OSX (For so many FF releases)

Quantum has seemingly killed this. I am running the same version cross the distros. Yet when I open in each distro, I have to enable the extensions again. This is not something that was an issue pre-Quantum

Yet when I open in each distro, I have to enable the extensions again. This is not something that was an issue pre-Quantum

?

Also, extensions.ini & extensions.json store OS specific paths & I gather that is the reason for your reinstall prompts?Perhaps run a script to rename those two files with appropriate copies of same for each OS prior to running SeaMonkey.See if that accomplishes anything?

created a chrome folder in my firefox profile (directory eg c:\firefox\<profile>\chrome\)copied the 3 files from the github link into that folderis it then a simple case of creating ProfileSharingWorkaround.uc.js and paste the code into that file (which will also be in the chrome folder)